2D metamaterial Luneburg lens for enhancing the RCS of chipless dielectric resonator tags

In this paper, a 2D Luneburg lens is proposed to improve the Radar Cross Section (RCS) of dielectric resonator (DR) tags, which would be used for an indoor localization system at THz frequencies where the low RCS of the tag makes the detection against clutter signals difficult. A Luneburg lens made of PTFE is fabricated using milling technique based on metamaterial concept, and characterized using a Vector Network Analyzer (VNA). Three ceramic resonators with different resonance frequencies are placed at different positions in the lens focal area to test the performance of the lens. To prove the concept, the simulation and measurement have been performed at scaled frequencies in the 4.5-7 GHz range. The RCS improvement is found to depend on the lens dimensions and frequencies of operation. A Luneburg lens with a height of 35 mm and a diameter of 66 mm boosts the RCS by 18 dB at 6.2 GHz.